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		<title>three.js webgl - GLTFloader + variants</title>
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	</head>

	<body>
		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - GLTFLoader + <a href="https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_variants" target="_blank" rel="noopener">KHR_materials_variants</a><br />
			<a href="https://github.com/pushmatrix/glTF-Sample-Models/tree/master/2.0/MaterialsVariantsShoe" target="_blank" rel="noopener">Materials Variants Shoe</a> by
			<a href="https://github.com/Shopify" target="_blank" rel="noopener">Shopify, Inc</a><br />
			<a href="https://hdrihaven.com/hdri/?h=quarry_01" target="_blank" rel="noopener">Quarry</a> from <a href="https://hdrihaven.com/" target="_blank" rel="noopener">HDRI Haven</a>
		</div>

		<script type="importmap">
			{
				"imports": {
					"three": "../build/three.module.js",
					"three/addons/": "./jsm/"
				}
			}
		</script>

		<script type="module">

			import * as THREE from 'three';

			import { GUI } from 'three/addons/libs/lil-gui.module.min.js';
			import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
			import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js';
			import { HDRLoader } from 'three/addons/loaders/HDRLoader.js';

			let camera, scene, renderer;
			let gui;

			const state = { variant: 'midnight' };

			init();
			render();

			function init() {

				const container = document.createElement( 'div' );
				document.body.appendChild( container );

				camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 0.25, 20 );
				camera.position.set( 2.5, 1.5, 3.0 );

				scene = new THREE.Scene();

				new HDRLoader()
					.setPath( 'textures/equirectangular/' )
					.load( 'quarry_01_1k.hdr', function ( texture ) {

						texture.mapping = THREE.EquirectangularReflectionMapping;

						scene.background = texture;
						scene.environment = texture;

						render();

						// model

						const loader = new GLTFLoader().setPath( 'models/gltf/MaterialsVariantsShoe/glTF/' );
						loader.load( 'MaterialsVariantsShoe.gltf', function ( gltf ) {

							gltf.scene.scale.set( 10.0, 10.0, 10.0 );

							scene.add( gltf.scene );

							// GUI
							gui = new GUI();

							// Details of the KHR_materials_variants extension used here can be found below
							// https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_variants
							const parser = gltf.parser;
							const variantsExtension = gltf.userData.gltfExtensions[ 'KHR_materials_variants' ];
							const variants = variantsExtension.variants.map( ( variant ) => variant.name );
							const variantsCtrl = gui.add( state, 'variant', variants ).name( 'Variant' );

							selectVariant( scene, parser, variantsExtension, state.variant );

							variantsCtrl.onChange( ( value ) => selectVariant( scene, parser, variantsExtension, value ) );

							render();

						} );

					} );

				renderer = new THREE.WebGLRenderer( { antialias: true } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.toneMapping = THREE.ACESFilmicToneMapping;
				renderer.toneMappingExposure = 1;
				container.appendChild( renderer.domElement );

				const controls = new OrbitControls( camera, renderer.domElement );
				controls.addEventListener( 'change', render ); // use if there is no animation loop
				controls.minDistance = 2;
				controls.maxDistance = 10;
				controls.target.set( 0, 0.5, - 0.2 );
				controls.update();

				window.addEventListener( 'resize', onWindowResize );

			}

			function selectVariant( scene, parser, extension, variantName ) {

				const variantIndex = extension.variants.findIndex( ( v ) => v.name.includes( variantName ) );

				scene.traverse( async ( object ) => {

					if ( ! object.isMesh || ! object.userData.gltfExtensions ) return;

					const meshVariantDef = object.userData.gltfExtensions[ 'KHR_materials_variants' ];

					if ( ! meshVariantDef ) return;

					if ( ! object.userData.originalMaterial ) {

						object.userData.originalMaterial = object.material;

					}

					const mapping = meshVariantDef.mappings
						.find( ( mapping ) => mapping.variants.includes( variantIndex ) );

					if ( mapping ) {

						object.material = await parser.getDependency( 'material', mapping.material );
						parser.assignFinalMaterial( object );

					} else {

						object.material = object.userData.originalMaterial;

					}

					render();

				} );

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

				render();

			}

			//

			function render() {

				renderer.render( scene, camera );

			}

		</script>

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